They were among 13 people who have been killed so far this month. That is more than double the number of criminal homicides recorded in all of October last year, according to an IndyStar analysis of crime records. Most of those cases are unsolved.

“Since 2010, unfortunately, we’ve seen an increase in violence that is unacceptable,” IMPD Sgt. Kendale Adams told IndyStar. He emphasized the department’s focus on beat policing and hiring new officers to counter the rising tide of violence.

IMPD released the booking photo of Cody Weir, 25, of Avon. Weir is a suspect in the killing of 23-year-old Carina Rodriguez in a Downtown apartment building's fitness center.(Photo: Provided/IMPD)

Rodriguez and Castro were killed one week apart in unusual circumstances. Both, it appears, were victims of random attacks.

On Tuesday morning, the man accused of killing Castro, 37-year-old Jason Cooper, appeared in Marion Superior Court for a preliminary hearing.

With his hands cuffed in front of him, Cooper entered the court room’s back door to sit before the judge. He was informed that the state found probable cause for his arrest and that prosecutors had not yet filed formal criminal charges.

Those charges came by Tuesday afternoon. Cooper now faces charges of murder, robbery resulting in serious bodily injury, armed robbery and resisting law enforcement.

One gunshot wound hit Castro's head, the other to his "left flank," according to court documents. He also suffered at least three stab wounds, including one to the chest. Both gunshot wounds and the chest stab were considered lethal, but the Marion County coroner's office has not determined which caused his death.

In the parking lot, police said Cooper carjacked a vehicle from a 72-year-old woman. He led police on a chase that ended when he crashed that stolen car.

After the arrest, Cooper told police that he had snorted a line of methamphetamine, according to the affidavit. Police also described him as "dirty and unkempt" and said he was "nervous, twitching, speaking fast and was unable to focus on one topic."